Repeat request in a loop
Burp Intruder can do various kinds of fuzzing attacks with provided payloads. And the Burp repeater can repeat requests. However if you need to repeat a certain request in a loop again and again then here is the technique to do it. This is done through the Burp Intruder with "Null payloads".
1. Select your request in the Proxy tab and click "Send to Intruder".
2. In Intruder, in the Positions tab click "Clear" to clear all positions. We do not want to provide payloads for any position, just repeat the request.
3. In the Payloads tab, select Payload type : "Null payloads". In the next section of "Payload Options" select "Continue indefinitely". This will generate infinite number of payloads but since we have not specified any position, the payload will not be applied anywhere in the request. If you want to repeat the request for a specific number of times then put a number in the "Generate _____ payloads" box. It will then loop only that many times.
4. Click "Intruder > Start attack" in the top menu to start the attack.
Now the request would keep repeating according to the above provided settings.